Apparatus and method for rendering digital content

ABSTRACT

An apparatus for rendering a digital content having license information defining specifics of permission of a rendering operation includes a license processor that acquires, from the license information of the digital content, a constraint defining conditions for rendering between the digital content and other digital content; an operation execution command generator that generates an operation execution command for rendering the digital content according to the constraint acquired by the license processor; and a content renderer that renders the digital content based on the operation execution command generated by the operation execution command generator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 11/076,538 filed Mar. 10, 2005, which is based upon and claims thebenefit of priority from the prior Japanese Patent Application No.2004-287627 filed on Sep. 30, 2004. The entire contents of both of thoseapplications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1) Field of the Invention

This invention relates to a digital content rendering apparatus, adigital content rendering method for rendering a digital content basedon the license information defining the specifics of permission of therendering operation.

2) Description of the Related Art

In recent years, a multiplicity of DRMs (Digital Right Managements)providing a technique for protecting the copyright of a digital workhave been developed. Especially, the commercial digital contents formovies and music, as represented by DVD, have been developed with thecopyright strongly protected in a form advantageous to the contentsprovider.

The function of these techniques to protect the copyright is provided asa very rigid and stubborn mechanism in the presence of a strong desireto prevent the duplication of digital contents, and limits the freedomof the user more than analog contents.

The copyright law lays downs a provision of what is called the fair usewhereby a work can be used without permission of the copyright holder byduplication or citation for private use. As to digital works, however,the freedom of the user is limited to prevent the duplication asdescribed above, and therefore the duplication or citation for privateuse is prohibited. In view of this, the desire has increased for thefair use of digital works.

On the other hand, the copyright protection of non-commercial contentssuch as business documents, product catalogs, personal home pages,electronic mails, or the like with the contents thereof routinely reusedand secondarily processed currently draws less attention, and thereforethese contents have yet to be safely distributed.

In this situation, the activities are being carried out forinternational standardization such as ISO/IEC 21000 (MPEG21) aimed atthe distribution and management of various forms of digital contents.With regard to MPEG21, a digital item declaration language (DIDL) forexpressing the composite content configured of a combination andconnection of a plurality of contents has been standardized, whereby thecomposite content including a plurality of contents as componentelements has become possible to handle. Further, a right expressionlanguage (REL) making possible flexible license description has alsobeen standardized, and a supporting method for describing the licenseusing REL has been proposed by USP Application Pub. No. US2003/0125976.

A technique for synthesizing a CM image and a video content andrendering a composite content using the information such as the age,sex, distribution history and purchase history of the user of thecontent has been proposed in Japanese Patent Application Laid-Open No.2002-203119.

When the distribution and reuse of a composite content is intended,however, the assumption is required that the elements constituting theparticular composite content are distributed and reused as individualcontents or synthesized with other different contents for rendering. Insuch a case, the context information including the position as viewedfrom the whole or the relationship with other component elements isliable to be lost by the individual use of the component elements. As aresult, the original intention of the author may be expressederroneously or transmitted as insignificant information.

It may be considered that this inconvenience can be avoided byintegrating the component elements indivisibly. Each component element,however, may be a complete work itself and not necessarily require othercomponent elements. From the viewpoint of distribution of digitalcontents that can be readily reused, the process of integrating thecomponent elements indivisibly leads to an increased cost of editing andright handling and rather constitutes a stumbling block to the soundredistribution of contents.

MPEG21/DIDL has a mechanism for expressing the structural information ofthe composite content while at the same time selecting the componentelements to be rendered and excluding the other component elements atthe time of rendering. When the composite content is distributed bydivision, the original structure cannot be restored. According to thetechnique of USP Application Pub. No. US2003/0125976 using MPEG21/REL,the use license can be set for each component element of the compositecontent, but the license description including the correlation betweenthe contents is impossible.

In the technique described in Patent Application Laid-Open No.2002-203119, the contents are individually synthesized based on the userinformation. This is not a mechanism for protecting the intention of theauthor, and once it is decomposed again and the component elements aredistributed, the original structure cannot be restored.

SUMMARY OF THE INVENTION

It is an object of the present invention to at least solve the problemsin the conventional technology.

An apparatus for rendering a digital content having license informationdefining specifics of permission of a rendering operation according toone aspect of the present invention includes a license processor thatacquires, from the license information of the digital content, aconstraint defining conditions for rendering between the digital contentand other digital content; an operation execution command generator thatgenerates an operation execution command for rendering the digitalcontent according to the constraint acquired by the license processor;and a content renderer that renders the digital content based on theoperation execution command generated by the operation execution commandgenerator.

A method of rendering a digital content having license informationdefining specifics of permission of a rendering operation according toanother aspect of the present invention includes acquiring, from thelicense information of the digital content, a constraint definingconditions for rendering between the digital content and other digitalcontent; generating an operation execution command for rendering thedigital content according to the constraint; and rendering the digitalcontent based on the operation execution command.

The computer program product according to still another aspect of thepresent invention causes a computer to perform the method according tothe present invention.

The other objects, features, and advantages of the present invention arespecifically set forth in or will become apparent from the followingdetailed description of the invention when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram that depicts a configuration of the digitalcontent rendering apparatus according to an embodiment;

FIG. 2 is a diagram that explains the distribution image of thecomposite content;

FIG. 3A is a diagram that explains the description model of aconstrained operation;

FIG. 3B is a diagram that explains the description model of acomplementary constraint;

FIG. 3C is a diagram that explains the description model of an exclusiveconstraint;

FIG. 4A is a schematic diagram that depicts an example of the renderingimage of the composite content having a constraint;

FIG. 4B is a schematic diagram that depicts an example of the renderingimage of the composite content having a constraint;

FIG. 4C is a schematic diagram that depicts an example of the renderingimage of the composite content having a constraint;

FIG. 5A is a schematic diagram that depicts an example of the contentdata described in MPEG21 form;

FIG. 5B is a schematic diagram that depicts an example of the contentdata described in MPEG21 form;

FIG. 5C is a schematic diagram that depicts an example of the contentdata described in MPEG21 form;

FIG. 6A is a schematic diagram that depicts an example of the licensedata described in XML form;

FIG. 6B is a schematic diagram that depicts an example of the licensedata described in XML form;

FIG. 6C is a schematic diagram that depicts an example of the licensedata described in XML form;

FIG. 7 is a diagram that explains an example of the constraintrelationship dictionary;

FIG. 8 is a diagram that explains an example of the operation table;

FIG. 9 is a diagram that explains an example of the time constrainttable (TCT);

FIG. 10 is a diagram that explains an example of the spatial constrainttable (SCT);

FIG. 11 is a diagram that explains an example of the command statementdata;

FIG. 12 is a flowchart that depicts the content rendering process in thedigital content rendering apparatus according to this embodiment;

FIG. 13 is a flowchart that depicts the license processing in thedigital content rendering apparatus according to this embodiment;

FIG. 14 is a flowchart that depicts the execution command generatingprocess in the digital content rendering apparatus according to thisembodiment;

FIG. 15 is a flowchart that depicts the exclusive constraint checkingprocess in the digital content rendering apparatus according to thisembodiment;

FIG. 16 is a flowchart that depicts the time constraint table (TCT)generating process in the digital content rendering apparatus accordingto this embodiment;

FIG. 17 is a flowchart that depicts the spatial constraint table (SCT)generating process in the digital content rendering apparatus accordingto this embodiment;

FIG. 18 is a flowchart that depicts an outline of the condition tablemerging process in the digital content rendering apparatus according tothis embodiment;

FIG. 19A is a flowchart that depicts the condition table merging processin the digital content rendering apparatus according to this embodiment;

FIG. 19B is a flowchart that depicts the condition table merging processin the digital content rendering apparatus according to this embodiment;

FIG. 20 is a flowchart that depicts an outline of the execution sequencegenerating process in the digital content rendering apparatus accordingto this embodiment;

FIG. 21 is a flowchart that depicts an outline of the execution sequencegenerating process in the digital content rendering apparatus accordingto this embodiment;

FIG. 22 is a flowchart that depicts the command statement generatingprocess in the digital content rendering apparatus according to thisembodiment;

FIG. 23 is a flowchart that depicts the content rendering process in thedigital content rendering apparatus according to this embodiment;

FIG. 24 is a schematic diagram that depicts an example of contentrendering in the digital content rendering apparatus according to thisembodiment;

FIG. 25 is a schematic diagram that depicts an example of contentrendering in the digital content rendering apparatus according to thisembodiment;

FIG. 26 is a schematic diagram that depicts an example of contentrendering in the digital content rendering apparatus according to thisembodiment;

FIG. 27 is a schematic diagram that depicts an example of contentrendering in the digital content rendering apparatus according to thisembodiment; and

FIG. 28 is a schematic diagram that depicts an example of contentrendering based on the structural constraint in the digital contentrendering apparatus according to this embodiment.

DETAILED DESCRIPTION

With reference to the accompanying drawings, a digital content renderingapparatus, a digital content rendering method, a digital contentrendering program and a recording medium for recording the digitalcontent rendering program according to a preferred embodiment of theinvention are described in detail below.

The digital content rendering apparatus according to this embodiment isadapted to acquire the constraint described in the license informationof the content and render the digital content in such a manner as tosatisfy the constraint thus acquired.

FIG. 1 is a block diagram that depicts the configuration of a digitalcontent rendering apparatus 100 according to this embodiment. As shownin FIG. 1, the digital content rendering apparatus 100 comprises acontent storage controller 101, a content designation receiver 102, alicense processor 103, a use condition determining unit 104, a contentrenderer 105, an operation execution command generator 106, a renderinghistory data storage unit 107 and a user I/F 108. Also, the digitalcontent rendering apparatus 100 according to this embodiment holds aconstraint relationship dictionary 109 in a hard disk drive (HDD).Further, the digital content rendering apparatus 100 holds an operationtable 111, a time constraint table (TCT) 112, a spatial constraint table(SCT) 113, command statement data 114 and rendering history data 115 ina RAM (random access memory) 110.

In the digital content rendering apparatus 100 according to thisembodiment, an operatively interlocked relationship is assured betweenthe content storage controller 101 that reads the content 120 and thelicense information 121 of the content, the content designation receiver102 that receives the content designated for rendering by the user fromthe content read, the license processor 103 that acquires the useconditions and the constraint from the license information 121 of thecontent 120 that has received the designation for rendering andgenerates an operation execution command and renders the contentaccording to the use conditions and the constraint, the use conditiondetermining unit 104, the content renderer 105, the operation executioncommand generator 106 and the rendering history data storage unit 107.The detailed structure of the license information 121 of the content isexplained in detail later.

The content storage controller 101 reads the content 120 designated bythe user and the license information 121 of the content from the userI/F 108, and stores them in the storage unit such as a RAM 110 in thedigital content rendering apparatus 100.

The content designation receiver 102 displays a list of the contentsstored in the content storage controller 101 on the user I/F 108, andreceives the content designated by the user from the contents displayed.

The license processor 103 acquires the use conditions and the constraintfrom the license information 121 of the content corresponding to thecontent ID received from the content designation receiver 102,determines the constraint and whether the use conditions for renderingare satisfied and prepares the operation table 111. The content ID isdefined as information for uniquely identifying the content. Thedetailed structure of the operation table 111 is explained later.

The use condition determining unit 104 determines from the useconditions described in the license information 121 of the contentwhether the content can be rendered.

The operation execution command generator 106 receives the operationtable 111 prepared by the license processor 103, and while accessing tothe information on the content stored in the rendering history data 115and being rendered and the relationship between the constraints held inthe constraint relationship dictionary 109, generates an operationexecution command that satisfies the constraints stored in the operationtable 111 received.

The rendering history data storage unit 107 holds the rendering historydata 115. The rendering history data 115 holds the content ID of thecontent being rendered.

The content renderer 105 reads the required content from the storageunit in which it is stored by the content storage controller 101, basedon the operation execution command generated by the operation executioncommand generator 106, and renders the content thus read.

The user I/F 108, including a display unit such as a display and aninput device such as a keyboard or a mouse, displays a screen forselecting the content or a screen (not shown) for rendering the content,while at the same time receiving the input operation from these screens.

The constraint relationship dictionary 109 is a data file storing therelationship between the constraints, and contains the definition of theconstraint contrary to a given constraint as a relationship between theconstraints. The detailed structure of the constraint relationshipdictionary 109 is described later.

The RAM 110 is a memory capable of random access, and functions as astorage unit that stores the operation table 111, the TCT 112, the SCT113, the command statement data 114 and the rendering history data 115.

The operation table 111 stores the operation permitted for rendering ofeach content making up a component element of the composite content andthe type of a constraint that may exist. The detailed structure of theoperation table 111 is described later.

The TCT 112 stores the result of extracting the time constraint, whichis one of the constraints, from the operation table 111 on the one handand stores the result of merging the stored time constraint with aspatial constraint, which is another one of the constraints, on theother hand. The TCT 112 is further used for storing the executionsequence generated from the merged constraints. The detail of the timeconstraint and the spatial constraint and the detailed structure of theTCT 112 are described later.

The SCT 113 stores the result of extracting the spatial constraint,which is one of the constraints, from the operation table 111. Thedetail of the spatial constraint and the detailed structure of the SCT113 are described later.

The command statement data 114 stores the command statement forexecuting the content rendering, which text is generated by convertingthe execution sequence stored in the TCT 112. The detailed structure ofthe command statement data is described later.

FIG. 2 is a schematic diagram that depicts the manner in which theelements making up the composite content are distributed and reusedindividually as units. In the case shown in FIG. 2, the content A isdecomposed into the component elements including the contents A1 to A4.Of these contents, the contents A1 to A3 are synthesized with anothercontent B1 to generate a content B. Also, the contents A2, A3, B1 makingup the component elements of the content B and the content A4 making upthe component element of the content A are reused and synthesized withanother content C1 to generate a content C.

When the context information including the position as viewed from thecontent A as a whole and the relationship with other elements is definedbetween the contents A1 and A4 making up the component elements of thecontent A in the case shown in FIG. 2, the digital content renderingapparatus 100 according to this embodiment can render the contents B andC while protecting the particular context information.

In FIG. 3A, the definition of the constraint is expressed in the form ofXML Schema. According to this embodiment, the constraint 311 is based onREL of MPEG21 and defined in the form of an extension of REL of MPEG21.Specifically, as shown in FIG. 3A, the permit operation“playWithConstraint” is defined as an extension of the “Right” (permitoperation) element in REL of MPEG21 in such a manner as to designate oneor both of the two constraints including the complementary constraint312 and the exclusive constraint 313. In this way, the permit operationextended to attach a constraint to the permit operation (“Right”) in RELof MPEG21 corresponds to the constraint according to the invention.

The complementation and the exclusion are not generally establishedinteractively, but only in one direction. When the constraint isdesignated interactively, the complementary constraint or the exclusiveconstraint is required to be defined mutually.

In this embodiment, the constraint is indicated in the form of XML.Alternatively, however, the constraint may be expressed in the format oftable, relational data base or semantic network.

FIG. 3B shows the definition of the complementary constraint 312 in FIG.3A in the form of XML Schema. The complementary constraint is toforcibly recover a constraint content subjected to the constraint at thesame time as the main content, when rendering the main content subjectedto the constraint. The complementary constraint 321 is expressed by theconstraint content 322 and the constraint type as a pair. The constrainttype designates one or both of the time constraint type 323 and thespatial constraint type 324 or one or both of the time constraint type323 and the structural constraint type 325.

Specifically, although the time constraint type 323 and otherconstraints can be designated at the same time, the spatial constrainttype 324 and the structural constraint type 325 cannot be designated atthe same time. According to this embodiment, the designation of thespatial constraint is explained. Also when the structural constraint isdesignated, however, the digital contents can be rendered in such amanner as to satisfy the constraints by the same procedure as when thespatial constraint is designated.

As for the time constraint type 323, one of (1) “synchronous” (the maincontent and the constraint content are rendered synchronously), (2)“after” (the main content is rendered after the constraint content), and(3) “before” (the main content is rendered before the constraintcontent).

As for the spatial constraint type 324, on the other hand, one of thetypes can be designated, including (1) “above” (the main content isarranged above the constraint content), (2) “below” (the main content isarranged below the constraint content), (3) “rightSide” (the maincontent is arranged on the right side of the constraint content), (4)“leftSide” (the main content is arranged on the left side of theconstraint content), (5) “backward” (the main content is arranged behindthe constraint content), (6) “forward” (the main content is arranged infront of the constraint content), (7) “anywhere” (the main content isarranged at any place), and (8) “predefined stylesheet” (the maincontent is arranged based on the data containing the description ofarrangement).

As for the structural constraint type 325, any one of (1) “isContained”(a constraint content is included as an element of the main content) and(2) “isPartOf” (the main content is included as an element of theconstraint content) can be designated.

The constraint type is not limited to those described above, but may befurther extended. Some content types can be configured such that aspecific constraint type cannot be defined. When the contentsconstrained by each other are both still images, for example, the timeconcept is not applicable and therefore a configuration may be employedin which the time constraint type cannot be set. Also, when the contentsconstrained by each other are both audio contents, on the other hand,the spatial concept is not applicable, and therefore a configuration maybe employed in which the spatial constraint type cannot be set. In sucha case, the constraint type such as MimeType that can be set based onthe characteristic of the content can be limited.

FIG. 3C shows the definition of the exclusive constraint 313 in FIG. 3Ais expressed in the form of XML Schema. The exclusive constraintprohibits the existence of the constraint content when rendering themain content. The exclusive constraint 331 is expressed by theconstraint content 332 and the constraint type as a pair. The exclusiveconstraint type 333 (“exclusive”) can be designated as a constrainttype.

FIGS. 4A to 4C are schematic diagrams that depict an example ofrendering the component elements of the composite content with adesignated constraint in the digital content rendering apparatus 100according to this embodiment. In FIGS. 4A to 4C, a complementaryconstraint is defined from the content B to the content A and anexclusive constraint between the contents B and C.

FIG. 4A shows that only the content A is rendered when the rendering ofonly the content A is designated under the constraint described above.FIG. 4B shows that the content A is forcibly recovered and rendered atthe same time as the content B according to the complementary constraintwhen the rendering of only the content B is designated under theconstraint. FIG. 4C shows that the rendering of the content B isrejected due to the extrusive constraint when the rendering of thecontent B is designated under the constraint in a situation where thecontent C is already rendered.

FIG. 5A shows an example of describing the definition of the data of thecontent A shown in FIGS. 4A to 4C in the form of XML specified by DIDLof MPEG21. The license information 121 of the content A is described inthe license information description area 512 contained in the data 511of the content A.

FIG. 5B shows an example of describing the definition of the data of thecontent B shown in FIGS. 4A to 4C in the form of XML defined in DIDL ofMPEG21. The license information 121 of the content B is described in thelicense information description area 522 contained in the data 521 ofthe content B.

FIG. 5C shows an example of describing the definition of the data of thecontent C shown in FIGS. 4A to 4C in the form of XML defined in DIDL ofMPEG21. The license information 121 of the content C is described in thelicense information description area 532 contained in the data 531 ofthe content C.

FIGS. 6A to 6C show an example in which the data structure of thelicense information 121 of the content in FIG. 1 is described in theform extended for description of the constraint based on the formdefined by REL of MPEG21. The description (611, 621, 631) of all thegrants of permission defines each element of the principal having theright to use, the permit operation (“Right”) and the use condition basedon REL of MPEG21.

The license information 611 in FIG. 6A shows the detailed description ofthe license information description area 512 shown in FIG. 5A. Thelicense information 611 has no special description of constraint but thepermit operation 612 (“play”) for normal rendering.

The license information 621 in FIG. 6B shows the detailed description ofthe license information description area 522 shown in FIG. 5B. Thepermit operation 622 includes the description of two constraints (623,624) as constraints between the contents, which represent the extensionof the current REL of MPEG21. The constraint 623 includes twocomplementary constraints, namely the time constraint (“synchronous”)and the spatial constraint (“backward”). The constraint 624, on theother hand, includes the description of the exclusive constraint(“exclusive”).

The license information 631 in FIG. 6C shows the detailed description ofthe license information description area 532 shown in FIG. 5C. Thepermit operation 632 includes the description of the exclusiveconstraint 633 (“exclusive”) between the contents, and represents anextension of current REL of MPEG21.

FIG. 7 is a diagram that explains an example of the structure of theconstraint relationship dictionary 109. As shown in the example in FIG.7, the constraint relationship dictionary 109 stores the operationopposite to a given operation. As an opposite operation to “above”indicating the operation of arranging the main content above, forexample, “below” for arranging the main content below is stored. Fromthe relationship between the constraints stored in the constraintrelationship dictionary 109, the substantially same constraintdesignated between two contents is found out and the double operation isexcluded.

FIG. 8 is a diagram that explains an example of the structure of theoperation table 111. As shown by the example in FIG. 8, the operationtable 111 stores the permit operation (“Right”), the content ID (ID1) ofthe main content, the content ID (ID2) of the constraint content, theconstraint type (“Op-Type”) and a flag (“ExistenceCheck”) indicatingwhether the main content is being rendered.

The permit operation designates the operation permitted when using thecontent, and stores the specifics of the “Right” (permit operation)element in REL of MPEG21. In the digital content rendering apparatus 100according to this embodiment, “rendering” defined according to thestandard of REL of MPEG21 or “playWithConstraint” defined by extendingREL of MPEG21 is set as the permit operation.

The content ID of the constraint content and the constraint type are setonly when “playWithConstraint” (the permit operation extended to have aconstraint) is set as a permit operation. In other cases, “nil” is set.The constraint type is set as a value defined corresponding to the typeof the constraint such as the time constraint, the spatial constraint orthe structural constraint.

The flag indicating whether the main content is being rendered is usedfor the process of suppressing the generation of the operation executioncommand of the content being rendered for the content being rendered,and set to “true” while in rendering and “false” while not in rendering.

FIG. 9 is a diagram that explains an example of the structure of thetime constraint table (TCT) 112. The TCT 112 stores the time constraintfor content rendering with the contents IDs arranged from left to rightin the order of rendering or with “&” attached after two content IDs ofthe contents rendered at the same time. As shown in FIG. 9, for example,assume that the content B is rendered before the content A. The data“(B)(A)” is stored in the TCT 112. Similarly, when the content D isrendered before the content C, the data “(D)(C)” is stored, and when thecontent E is rendered at the same time as the content F, the data“(EF&)” is stored in the TCT 112.

FIG. 10 is a diagram that explains an example of the structure of thespatial constraint table (SCT) 113. As shown in FIG. 10, the SCT 113stores the data with the description of the constraint type between twocontent IDs when the spatial constraint is designated between the twocontents of the two content IDs. When the spatial constraint is notdesignated, on the other hand, the data with the description of theindividual content IDs is stored. When the content A is arranged belowthe content B for rendering as shown in FIG. 10, for example, the data“(A below B)” is stored in SCT 113. Similarly, when the content B isarranged on the right side of the content C for rendering, the data “(BrightSide C)” is stored in the SCT 113. Also, when the spatialconstraint is not designated for the content D, the data “(D)” is storedin the SCT 113.

FIG. 11 is a diagram that explains an example of the structure of thecommand statement data 114. The command statement data 114 storesrendering commands in the order of rendering according to the executionsequence generated after merging the TCT 112 and the SCT 113 with eachother. Specifically, a text with “Play” attached before the executionsequence generated is stored as a command statement. When the executionsequence is “(C below D below E)”, for example, the data “Play(C below Dbelow E)” is stored in the command statement data 114 as a commandstatement.

The process of rendering the content by the digital content renderingapparatus 100 according to this embodiment configured as described aboveis explained. FIG. 12 is a flowchart that depicts a general flow of thecontent rendering process according to this embodiment.

The content storage controller 101 reads the content data of the content120 designated by the user for rendering and the license information 121of the content (step S1201). The content 120 and the license information121 of the content may be integrated in the same file or stored indifferent files. Also, the content 120 may be read as a local contentfrom a HDD or the like storage medium or by being downloaded from anexternal server through a network.

The content which the user wants to render is selected and received fromthe contents making up the component elements of the content read by thecontent designation receiver 102 (step S1202). The content designationreceiver 102 delivers the content ID of the received content to thelicense processor 103 (step S1203).

The license processor 103 analyzes the license information 121 of thecontent corresponding to the received content ID, and processes thelicense by determining the use conditions or solving the constraint forrendering thereby to generate an operation table 111 (step S1204). Thedetail of the license processing is explained later.

The license processor 103 determines whether the generated operationtable 111 is empty (step S1205). When the operation table 111 is empty(YES: at step S1205), the user I/F 108 indicates the message to theeffect that the content cannot be rendered (step S1206). When theoperation table 111 is not empty (NO: at step S1205), on the other hand,the operation execution command generator 106 executes the operationexecution command generating process for generating an operationexecution command satisfying the constraint stored in the operationtable 111 (step S1207). The detail of the operation execution commandgenerating process is explained later.

After generating the operation execution command, the operationexecution command generator 106 determines whether the command statementdata 114 is empty (step S1208). When the command statement data 114 isempty (YES: at step S1208), the user I/F 108 indicates the message tothe effect that the content cannot be rendered (step S1206). When thecommand statement data 114 is not empty (NO: at step S1208), on theother hand, the content renderer 105 renders the content based on thegenerated operation execution command (step S1209). The detail of thecontent rendering process is explained later.

After rendering the content, the user I/F 108 determines whether theuser has selected the end of rendering (step S1210). When the renderingend is not selected (NO: at step S1210), the standby mode for contentselection is entered. When the rendering end is selected (YES: at stepS1210), on the other hand, the content rendering process is completed.

The detail of the license processing shown at step S1204 in FIG. 12 isexplained. FIG. 13 is a flowchart that depicts a general flow of thelicense processing. The license processing is executed recursively bythe interlocked operation of the license processor 103 and the usecondition determining unit 104 (step S1315).

The license processor 103 receives the content ID from the contentdesignation receiver 102 (step S1301). Next, the process of steps S1302to S1310 is executed for all the contents making up the componentelements of the content corresponding to the received content ID.

The license processor 103 reads the license information 121 of thecontent making up the component element (step S1302) and determineswhether the rendering permit information exists (step S1303). In theabsence of the rendering permit information (NO: at step S1303), it isdetermined whether all the contents have been processed. In the presenceof the rendering permit information (YES: at step S1303), on the otherhand, the use condition contained in the rendering permit information isacquired and delivered to the use condition determining unit 104 (stepS1304).

The use condition determining unit 104, based on the use conditionreceived, determines whether the content satisfies the use conditions,and returns the result of determination to the license processor 103(step S1305). The use conditions contain the description of suchconditions as the valid period, the charging method, the price and thecovered area. The use conditions may be determined internally using theenvironmental information in the digital content rendering apparatus 100or using an external ASP, or the like through a network. Further, theprocess may include a dialog for presenting the use conditions andprompting the user to agree thereon.

Based on the result of determination returned from the use conditiondetermining unit 104, the license processor 103 determines whether thecontent satisfies the use condition (step S1306). When the useconditions are not satisfied (NO: at step S1306), the process proceedsto the determination whether all the contents have been processed. Whenthe use conditions are satisfied (YES: at step S1306), on the otherhand, the process proceeds to the determination whether a constraintexists (step S1307).

In the absence of the constraint (NO: at step S1307), the licenseprocessor 103 adds the data free of the constraint to the operationtable 111 (step S1308). Specifically, the permit operation (“play”) freeof the constraint is set as the permit operation (“Right”), the contentID of the content being processed is set as the content ID (ID1) of themain content, “Nil” is set as the content ID (ID2) of the constrainedcontent and the constraint type (“Op-Type”), and the “false” is set as“ExistenceCheck” and then they are added as data to the operation table111.

In the presence of the constraint (YES: at step S1307), on the otherhand, the license processor 103 adds the data containing the constraintto the operation table 111 (step S1309). Specifically, the permitoperation (“playWithConstraint”) extended to have the constraint is setas the permit operation (“Right”), the content ID of the content beingprocessed is set as the content ID (ID1) of the main content, thecontent ID of the content subjected to constraint is set as the contentID (ID2) of the constraint content, the constraint type acquired fromthe license information 121 of the content is set as the constraint type(“Op-Type”), and “false” is set in “ExistenceCheck”, and then they areadded as data to the operation table 111.

After adding the data to the operation table 111, the license processor103 determines whether all the contents have been processed (stepS1310), and when all the contents have been processed (YES: at stepS1310), the process proceeds to the next step. When all the contentshave not been processed (NO: at step S1310), on the other hand, theprocess proceeds to the step of reading the contents of the remainingcomponent elements (step S1302).

The license processor 103 executes the process of steps S1311 to S1316to detect the constraints from the license information 121 of thecomplementary constraint contents and extract the contents required tobe recovered at the same time.

The license processor 103 acquires the operation data from the operationtable 111 (step S1311), and determines whether the acquired operationdata contains the exclusive constraint (step S1312). When the acquiredoperation data contains the exclusive constraint (YES: at step S1312),the contents to be recovered at the same time are not required to beextracted, and therefore the process proceeds to the next step.

When the acquired operation data contains no exclusive constraint (NO:at step S1312), on the other hand, it is determined whether theoperation data of the complementary contents are existent in theoperation table 111 (step S1313). It is determined, for example, whetherthe operation data having the same ID2 as ID1 of the operation databeing processed or the same ID1 as ID2 is existent, and when suchoperation data is existent (YES: at step S1313), the process proceeds tothe next step. This is in order to avoid the endless loop of extractionof constraints. In the absence of the corresponding operation data (NO:at step S1313), the contents ID of the complementary constraint contentsare delivered to the license processor 103 (step S1314) and the licenseis processed recursively in order to further detect the constraints(step S1315).

The license processor 103 determines whether all the operation data havebeen processed (step S1316), and when all the operation data have beenprocessed (YES: at step S1316), delivers the operation table 111 to theoperation execution command generator 106 (step S1317) thereby to endthe license processing. When all the operation data have not beenprocessed (NO: at step S1316), on the other hand, the next operationdata is acquired and the process is repeated (step S1311).

FIG. 14 is a flowchart that depicts an outline of the general flow ofthe operation execution command generating process shown at step S1207in FIG. 12.

The operation execution command generator 106 receives the operationtable 111 prepared by the license processor 103 (step S1401). Next, theoperation execution command generator 106 checks to see whether thecontent is being rendered, by referring to the specifics of therendering history data 115 and the operation table 111 received (stepS1402). Specifically, when any of the contents ID (ID1) of the maincontent of the operation data in the operation table 111 is equal to thecontent ID stored in the rendering history data 115, “ExistenceCheck” ofthe particular operation data is set to “true”.

When there is any content ID that exists in the rendering history data115 but not in the operation data, the operation data of the contentcorresponding to the particular content ID is newly added to theoperation table 111. In this case, “ExistenceCheck” is set as “true”.This data is accessed in the process of prohibiting the rendering of themain content while the exclusive constraint content is being rendered.

After that, the operation execution command generator 106 sequentiallyexecutes the steps of checking the exclusive constraint (step S1403),generating the time constraint table (TCT) (step S1404), generating thespatial constraint table (SCT) (step S1405), merging the condition table(step S1406), generating the execution sequence (step S1407) andgenerating the command statement (step S1408). The detail of these stepsis explained below.

FIG. 15 is a flowchart that depicts a general flow of the exclusiveconstraint checking process of step S1403 in FIG. 14.

The operation execution command generator 106 reads the operation datafrom the operation table 111 (step S1501), and when the read operationdata has an exclusive constraint, determines whether an exclusiveconstraint content is being rendered (step S1502). When an exclusiveconstraint content is being rendered (YES: at step S1502), the operationtable 111 is emptied (step S1503). This is by reason of the fact thatsince an exclusive constraint content is being rendered, the renderingof the main content designated for rendering is prohibited.

When no exclusive constraint content is being rendered (NO: at stepS1502), on the other hand, it is determined whether there exists aconstraint content designated as both exclusive and complementary at thesame time (step S1504). In the presence of such a constraint content(YES: at step S1504), the operation table 111 is emptied (step S1505).This is in order to prohibit the rendering of the main content since thedesignation of the same constraint content as both exclusive andcomplementary at the same time is contradictory.

The operation execution command generator 106 determines whether theoperation data defining an exclusive constraint exists in which thecontent ID of an exclusive constraint content not being rendered isdesignated as the content ID (ID1) of the main content (step S1506). Inthe presence of such operation data (YES: at step S1506), the particularoperation data is deleted from the operation table 111 (step S1507).This is because the constraint content not being rendered is exclusivewith respect to the main content and not required to be rendered.

The operation execution command generator 106 determines whether thereexists any content designated to have both the exclusive and thecomplementary constraint at the same time (step S1508). In the presenceof such a content (YES: at step S1508), the operation data designated tohave an exclusive constraint is deleted (step S1510). This is by reasonof the fact that in the presence of the operation data having acomplementary constraint, the operation execution command for renderingthe main content can be generated in the operation execution commandgenerating process described later, and therefore the operation datahaving the exclusive constraint already checked for exclusiveness is notrequired to be held any longer.

In the absence of the content designated to have both the exclusiveconstraint and the complementary constraint at the same time (NO: atstep S1508), on the other hand, the operation data designated to havethe exclusive constraint is rewritten into the operation data free ofthe constraint (step S1509). Specifically, the data is rewritten suchthat the permit operation (“play”) free of the constraint is as thepermit operation (“Right”) free of constraint, the content ID of theparticular content as the content ID (ID1) of the main content, “Nil” asthe content ID (ID2) and the constraint type (“Op-Type”) of theconstrained content, and “false” as “ExistenceCheck”. This is by reasonof the fact that the result of checking the exclusiveness shows that theparticular content can be rendered in the same manner as the contentfree of constraint.

The operation execution command generator 106 determines whether all theoperation data have been processed (step S1511), and when all theoperation data are not yet processed (NO: at step S1515), the nextoperation data is acquired and the process is repeated (step S1501).When all the operation data are processed (YES: at step S1511), on theother hand, the exclusive constraint checking process is completed.

FIG. 16 is a flowchart that depicts a general flow of the timeconstraint table (TCT) generating process of step S1404 in FIG. 14.

The operation execution command generator 106 reads the operation datafrom the operation table 111 (step S1601), and determines whether theconstraint type of the operation data thus read is “synchronous” (stepS1602).

When the constraint type of the operation data thus read is“synchronous”(YES: at step S1602), the operation execution commandgenerator 106 adds a list of the conditions for rendering the maincontent and the restrained content at the same time to the TCT 112 (stepS1603). Specifically, when the operation data read designates theconstraint for rendering the content A and the content B at the sametime, for example, the list “(AB&)” is added to the TCT 112. When theconstraint type of the operation data read is not “synchronous” (NO: atstep S1602), on the other hand, it is determined whether the constrainttype of the operation data read is “after” (step S1604).

When the constraint type of the operation data read is “after” (YES: atstep S1604), the operation execution command generator 106 adds thecondition for rendering the constrained content earlier to the TCT 112(step S1605). Specifically, when the operation data read designates theconstraint for rendering the content B constituting the constrainedcontent before the content A making up the main content, the list“(B)(A)” is added to the TCT 112. In this way, two lists in which thecontents rendered first are described on the left side and the contentsrendered next are described on the right side are added to the TCT 112.When the constraint type of the operation data read is not “after” (NO:at step S1604), it is determined whether the constraint type of theoperation data read is “before” (step S1606).

When the constraint type of the operation data read is “before” (YES: atstep S1606), the operation execution command generator 106 adds a listof conditions for rendering the constrained content later to the TCT 112(step S1607). Specifically, when the operation data read designates theconstraint for rendering the content A constituting the main contentbefore the content B making up the constrained content, the list“(A)(B)” is added to the TCT 112. When the constraint type of theoperation data read is not “before” (NO: at step S1606), on the otherhand, it is determined whether all the operation data have beenprocessed.

The operation execution command generator 106 determines whether the allthe operation data have been processed (step S1608), and when all theoperation data have not been processed (NO: at step S1608), the nextoperation data is acquired and the process is repeated (step S1601).When all the operation data have been processed (YES: at step S1608), onthe other hand, the record duplicated in the TCT 112 is deleted (stepS1609) thereby to end the time constraint table (TCT) generatingprocess.

FIG. 17 is a flowchart that depicts a general flow of the spatialconstraint table (SCT) generating process of step S1405 shown in FIG.14.

The operation execution command generator 106 reads the operation datafrom the operation table 111 (step S1701), and determines whether theoperation data read contains the spatial constraint (step S1702).

When the operation data read contains the spatial constraint (YES: atstep S1702), the operation execution command generator 106 adds therecord defining the spatial constraint to the SCT 113 (step S1703).Specifically, when the operation data read designates the constraint forrendering such that the content A constituting the main contentsatisfies the content B making up the constrained content and theconstraint type Op, for example, the list “(A Op B)” is added to the SCT113. The constraint type such as (1) “above”, (2) “below”, (3)“rightSide”, (4) “leftSide”, (5) “backward”, (6) “forward” or (7)“anywhere” is set as “Op”.

When the operation data read contains no spatial constraint (NO: at stepS1702), on the other hand, it is determined whether the operation dataread is free of constraint (step S1704).

When the operation data read is free of constraint (YES: at step S1704),the operation execution command generator 106 adds the record free ofconstraint to the SCT 113 (step S1705). Specifically, when the operationdata read is such as to render the content A individually free ofconstraint, for example, the list “(A)” is added to the SCT 113.

The operation execution command generator 106 determines whether all theoperation data have been processed (step S1706), and when all theoperation data have not been processed (NO: at step S1706), the nextoperation data is acquired and the process is repeated (step S1701).When all the operation data have been processed (YES: at step S1706), onthe other hand, the process proceeds to the next step.

At steps S1707 to S1710, the operation execution command generator 106extracts and deletes the records indicating substantially the samecondition from the records of the SCT 113 prepared.

A record is read from the SCT 113 (step S1707), and it is determinedwhether there exists any other record corresponding to the operationopposite to the operation of the record read (step S1708). Specifically,when the record read is “(A above B)”, for example, the operation“below” opposite to the operation “above” is acquired from theconstraint relationship dictionary 109, and it is determined whether therecord “(B below A)” generated by replacing the content ID for theopposite operation acquired is existent in the SCT 113.

In the presence of a record corresponding to the opposite operation(YES: at step S1708), the corresponding record is deleted from the SCT113 (step S1709). In the absence of a record corresponding to theopposite operation (NO: at step S1708), on the other hand, it isdetermined whether all the records have been processed (step S1710).When all the records have not been processed (NO: at step S1710), thenext record is read and the process is repeated (step S1707). When allthe records have been processed (YES: at step S1710), the spatialconstraint table (SCT) generating process is completed.

FIG. 18 is a flowchart that depicts an outline of a general flow of thecondition table merging process of step S1406 shown in FIG. 14.

The operation execution command generator 106 merges the list of the SCT113 and the list of the TCT 112 that have the same leading element (stepS1801).

The “leading element” is defined as the content ID described on the leftside of the list, or the content ID, if any, which is the only contentID designated. In the list “(A below B)”, for example, “A” is theleading element. Similarly, “C” is the leading element in the list“(C)”.

A list containing the spatial constraint of the content required to berendered after a given content is moved behind the list of the contentsto be rendered earlier (step S1802). Further, a list containing thespatial constraint of the content required to be rendered before a givencontent is moved before the list of the contents rendered later (stepS1803). After that, all the remaining records of the SCT 113 are addedas new records of the TCT 112 (step S1804). Finally, a list describingthe condition for rendering the content required to be rendered before agiven content is inserted before the list of the contents rendered later(step S1805). The detailed process at steps S1801 to S1803 and S1805 isdescribed later.

FIGS. 19A and 19B are flowcharts that depict a general flow of thecondition table merging process of step A1406 shown in FIG. 14. Also,FIGS. 19A and 19B show the detailed process of steps S1801 to S1803 andS1805 of which the outline is explained with reference to FIG. 18.

Steps S1901 to S1905 indicate the detailed process of step S1801 in FIG.18. First, the operation execution command generator 106 reads therecord from the SCT 113 (step S1901). The SCT 113 stores each list asone record, and therefore to read one record is equivalent to readingone list. Next, all the lists in the TCT 112 having a leading element ofthe same value as the leading element of the list read are searched(step S1902), and it is determined whether a corresponding list exists(step S1903).

In the absence of a corresponding list (NO: at step S1903), it isdetermined whether all the records have been processed. In the presenceof a corresponding list (YES: at step S1903), on the other hand, all thecorresponding lists are replaced by the list read, which is deleted fromthe SCT 113 (step S1904).

When the list “(A below B)” is stored in the SCT 113 and the list“(B)(A)” is stored in the TCT 112, for example, the list “(B)(A)” of theTCT 112 is replaced by the list “(B)(A below B)”, which is deleted fromthe SCT 113.

The operation execution command generator 106 determines whether all therecords have been processed (step S1905), and when all the records havenot been processed (NO: at step S1905), the next record is acquired andthe process is repeated (step S1901). When all the records have beenprocessed (YES: at step S1905), on the other hand, the process proceedsto the next step.

Steps S1906 to S1910 represent the detailed process of step S1802 inFIG. 18. First, the operation execution command generator 106 reads arecord (list) from the SCT 113 (step S1906). Next, all the lists in theTCT 112 having, as a leading element, the same value as the thirdelement of the list read are searched (step S1907), and it is determinedwhether a corresponding list exists (step S1908).

The third element is defined as the content ID of the constrainedcontent in the spatial constraint. Specifically, it is the content ID“Y”in the list described in the form of “(X Op Y)” (“X”, “Y” indicate thecontent ID, and “Op” the constraint type).

In the absence of a corresponding list (NO: at step S1908), it isdetermined whether all the records have been processed. In the presenceof a corresponding list (YES: at step S1908), on the other hand, thelist read is added behind all the corresponding lists, and the list readis deleted from the SCT 113 (step S1909).

When the list “(A below B)” is stored in the SCT 113, and the list “B”in TCT 112, for example, the list “(A below B)” is added behind the list“B” of the TCT 112 to form the list “(B)(A below B)”, and the list “(Abelow B)” is deleted from the SCT 113.

The operation execution command generator 106 determines whether all therecords have been processed (step S1910), and when all the records havenot been processed (NO: at step S1910), the next record is acquired andthe process is repeated (step S1906). When all the records have beenprocessed (YES: at step S1910), the process proceeds to the next step.

Steps S1911 to S1915 represent the detailed process of step S1803 inFIG. 18. First, the operation execution command generator 106 reads therecord (list) from the SCT 113 (step S191). Next, all the lists in theTCT 112 having a third element of the same value as the first element ofthe list read are searched (step S1912) to determine whether acorresponding list exists (step S1913).

In the absence of a corresponding list (NO: at step S1913), it isdetermined whether all the records have been processed. In the presenceof a corresponding list (YES: at step S1913, on the other hand, the listread is added before all the corresponding lists, and the particularlist read is deleted from the SCT 113 (step S1914).

When the list “(A below B)” is stored in the SCT 113, and the list “(Cbelow A)” in the TCT 112, for example, the list “(A below B)” is addedbefore the list “(C below A)” of the TCT 112 to form the list “(A belowB)(C below A)”, and the list “(A below B)” is deleted from the SCT 113.

The operation execution command generator 106 determines whether all therecords have been processed (step S1915), and when all the records havenot been processed (NO: at step S1915), the next record is acquired andthe process is repeated (step S1911). When all the records have beenprocessed (YES: at step S1915), on the other hand, the process proceedsto the next step.

The next step S1916 is the same as step S1804 in FIG. 18. At step S1916,the process of adding all the remaining records of the SCT 113 as newrecords of the TCT 112 is executed. This is by reason of the fact thatthe list designating the contents rendered individually free ofconstraint and the contents existing only in the spatial constrainttable (SCT) 113 is not merged with the TCT 112 in the aforementionedprocess and therefore newly added to the TCT 112 in preparation forgeneration of the execution sequence processed based on the TCT 112. Thedetailed process of generating the execution sequence is describedlater.

Steps S1917 to S1923 represent the detailed process of step S1805 shownin FIG. 18. First, the operation execution command generator 106 readsthe record from the TCT 112 (step S1917). Next, the element list isacquired from the record read (step S1918).

The element list is defined as a unit containing the description ofindividual constraints and defined by parentheses. When the record is“(C)(B below C)(A below B)”, for example, “(C)”, “(B below C)” and “(Abelow B)” constitute element lists.

Another element list having the first element of the same value as thethird element in the element list is searched (step S1919) to determinewhether a corresponding list exists (step S1920).

In the absence of a corresponding list (NO: at step S1920), it isdetermined whether all the records have been processed. In the presenceof a corresponding list (YES: at step S1920), on the other hand, thefirst element of the corresponding list is inserted immediately beforethe element list acquired (step S1921).

When the list “(B below A)(A below C)” is stored in the TCT 112, forexample, the first element “(A)” of the list “(A below C)” is insertedbefore the list “(B below A)(A below C)” thereby to form the list “(A)(Bbelow A)(A below C)”.

The operation execution command generator 106 determines whether all thelists have been processed (step S1922), and when all the lists have notbeen processed (NO: at step S1922), the next list in the record isacquired, and the process is repeated (step S1918). When all the listshave been processed (YES: at step S1922), on the other hand, the processproceeds to the next step.

The operation execution command generator 106 determines whether all therecords have been processed (step S1923), and when all the records havenot been processed (NO: at step S1923), the next record is acquired, andthe process is repeated (step S1917). When all the records have beenprocessed (YES: at step S1923), on the other hand, the condition tablemerging process is completed.

FIG. 20 is a flowchart that depicts an outline of a general flow of theexecution sequence generating process of step S1407 shown in FIG. 14.

The operation execution command generator 106 connects the recordshaving the same last and first lists in the TCT 112 (step S2001).

The last list is defined as the element list existing at the right endof the record, and the first list the element list existing at the leftend of the record. When the record is “(C)(B below C)(A below B)”, forexample, the list “(C)” is the first list and the list “(A below B)” isthe last list.

The records having the same first list are connected to each other (stepS2002). Finally, the process of replacing the lists rendered in thereverse order and having the opposite operation is executed (stepS2003). The detailed process of steps S2001 to S2003 is explained later.

FIG. 21 is a flowchart that depicts a general flow of the executionsequence generating process of step S1407 shown in FIG. 14. FIG. 20shows the detailed process of steps S2001 to S2003 of which an outlinehas been explained with reference to FIG. 20.

Steps S2101 to S2105 represent the detailed process of step S2001 inFIG. 20. First, the operation execution command generator 106 reads therecord from the TCT 12 (step S2101). Next, all the records in the TCT112 having the last list identical with the first list of the recordread are searched (step S2102) to determine whether a correspondingrecord exists (step S2103).

In the absence of a corresponding record (NO: at step S2103), it isdetermined whether all the records have been processed. In the presenceof a corresponding list (YES: at step S2103), on the other hand, thelast lists of all the corresponding records are replaced by the recordread, which is deleted from the TCT 112 (step S2104).

When the record “(C)(B below C)(A below B)” and the record “(D)(C)” arestored in the TCT 112, for example, the last list “(C)” of the record“(D)(C)” is replaced by the record “(C)(B below C)(A below B)”, and therecord “(C)(B below C)(A below B)” is deleted, with the result that onlythe record “(D)(C)(B below C)(A below B)” remains.

The operation execution command generator 106 determines whether all therecords have been processed (step S2105), and when all the records havenot been processed (NO: at step S2105), the next record is acquired, andthe process is repeated (step S2101). When all the records have beenprocessed (YES: at step S2105), on the other hand, the process proceedsto the next step.

Steps S2106 to S2110 represent the detailed process of step S2002 inFIG. 20. First, the operation execution command generator 106 reads therecord from the TCT 112 (step S2106). Next, all the records in the TCT112 having a first list identical with the first list of the record readare searched (step S2107) to determine whether a corresponding recordexists or not (step S2108).

In the absence of a corresponding record (NO: at step S2108), it isdetermined whether all the records have been processed. In the presenceof a corresponding record (YES: at step S2108), on the other hand, thefirst lists of all the corresponding records are replaced by the recordread, which is deleted from the TCT 112 (step S2109).

When the record “(B below C)(A below B)” and the record “(B below C)(C)”are stored in the TCT 112, for example, the first list “(B below C)” ofthe record “(B below C)(C)” is replaced by the record “(B below C)(Abelow B)”, and the record “(B below C)(A below B)” is recorded, with theresult that only the record “(B below C)“(A below B)(C)” remains.

The operation execution command generator 106 determines whether all therecords have been processed (step S2110), and when all the records havenot been processed (NO: at step S2110), the next record is acquired, andthe process is repeated (step S2106). When all the records have beenprocessed (YES: at step S2110), on the other hand, the process proceedsto the next step.

Steps S2111 to S2113 represent the detailed process of step S2003 inFIG. 20. First, the operation execution command generator 106 reads therecord from the TCT 112 (step S2111). Then, the operation executioncommand generator 106 looks for a list in the read records having thereverse order of rendering and the opposite operation, and in thepresence of a corresponding list, replaces the operation.

Specifically, the operation execution command generator 106 looks for alist constituting a pattern “(X aa Y**)##(Y)” or “(X aa Y**)##(Y bbX**)”, acquires the operation “cc” opposite to “aa” from the constraintrelationship dictionary 109, and replaces “(X aa Y)” with “X” and “(Y)”with “(Y cc X)”, which “X”, “Y” designate the content ID, “aa”, “bb”,“cc” a constraint type, “**” a character string and “##” an elementlist.

In the case of the pattern “(X below Y)(Y)”, for example, “X” isrequired to be rendered below “Y” according to the spatial constraint“below” after rendering of “Y”. In spite of this, the rendering of “Y”is designated later, and therefore both the alteration of the order ofrendering and the conversion to the opposite operation are required.

When the record “(B below C)(A below B)(C)” is stored in the TCT 112,for example, the list “(B below C)” is replaced by “(B)”, and the list“(C)” by the list “(C above B)”. Thus, the whole record is replaced by“(B)(A below B)(C above B)”.

The operation execution command generator 106 determines whether all therecords have been processed (step S2113), and when all the records havenot been processed (NO: at step S2113), the next record is acquired, andthe process is repeated (step S2111). When all the records have beenprocessed (YES: at step S2113), on the other hand, the executionsequence generating process is ended.

FIG. 22 is a flowchart that depicts a general flow of the commandstatement generating process of step S1408 shown in FIG. 14.

The operation execution command generator 106 reads the record from theTCT 112 (step S2201). Further, an element list is acquired from therecord read (step S2202). Next, the acquired element list is convertedinto a command statement, and the command statement thus converted isset in the command statement data 114 (step S2203). Specifically, a textwith “Play” added before the element list acquired is set as a commandstatement. When the element list is “(X aa Y bb Z)”, for example,“Play(X aa Y bb Z)” is set as a command statement in the commandstatement data 114.

The operation execution command generator 106 determines whether all theelement lists have been processed (step S2204), and when all the elementlists have not been processed (NO: at step S2204), the next element listis acquired, and the process is repeated (step S2202). When all therecords have been processed (YES: at step S2204), on the other hand, itis determined whether all the records have been processed.

The operation execution command generator 106 determines whether all therecords have been processed (step S2205), and when all the records havenot been processed (NO: at step S2205), the next record is acquired, andthe process is repeated (step S2201). When all the records have beenprocessed (YES: at step S2205), on the other hand, the command statementgenerating process is ended.

FIG. 23 is a flowchart that depicts a general flow of the contentrendering process of step S1209 shown in FIG. 12.

The content renderer 105 receives the command statement data 114prepared by the operation execution command generator 106 (step S2301).Then, the content renderer 105 reads the command statement from thecommand statement data 114 received (step S2302), and determines whetherthe command statement is a spatial constraint (step S2303).

When the command statement is a spatial constraint (YES: at step S2303),the content renderer 105 renders the content according to the particularspatial constraint (step S2304). Specifically, when the commandstatement is “Play(A above B)”, for example, the content A is renderedin such a manner as to be arranged above the content B. When the commandstatement is not a spatial constraint (NO: at step S2303), on the otherhand, it is determined whether the command statement is free ofconstraint (step S2305).

When the command statement is free of constraint (YES: at step S2305),the content renderer 105 renders the particular content alone (stepS2306). Specifically, when the command statement is “Play(A)”, forexample, the content A alone is rendered. When the command statement isnot a constraint (NO: at step S2305), on the other hand, it isdetermined whether the command statement is a constraint forsimultaneous rendering (step S2307).

When the command statement is a constraint for simultaneous rendering(YES: at step S2307), the content renderer 105 renders the two contentsin synchronism with each other (step S2308). Specifically, when thecommand statement is “Play(AB&)”, for example, the content A and thecontent B are rendered at the same time. When the command statement isnot a constraint for simultaneous rendering (NO: at step S2307), on theother hand, the process proceeds to the next step.

The content renderer 105 notifies the rendering history storage unit 107that the content rendered is being rendered (step S2309). The renderinghistory data storage unit 107 adds the content ID of the notifiedcontent to the rendering history data 115.

The content renderer 105 determines whether all the command statementshave been processed (step S2310), and when all the command statementshave not been processed (NO: at step S2310), the next command statementis acquired, and the process is repeated (step S2302). When all thecommand statements have been processed (YES: at step S2310), on theother hand, the content rendering process is ended.

FIGS. 24 to 27 are diagrams for explaining an example of contentrendering executed according to the content rendering process describedabove in the digital content rendering apparatus 100 according to thisembodiment.

In the case of FIG. 24, the constraints between four contents includingthe contents A to D shown in FIG. 24A are defined. Specifically, theconstraint is defined for rendering the content A after the content Bbelow the content B, the constraint is defined for rendering the contentB below the content C and the constraint is defined for rendering thecontent C after the content D. FIGS. 24B to 24F show the contents ofeach table up to the execution sequence generation upon designation ofrendering of the content A in the presence of the constraint.

This constraint is described in each license information of the contentsA to D. First, each license information of these contents is read by thelicense processing (step S1204) to generate the operation table 111shown in FIG. 24B. By referring to this table, the TCT 112 shown in FIG.24C is generated by the time constraint table (TCT) generating process(step S1404), and the SCT 113 shown in FIG. 24D by the spatialconstraint table (SCT) generating process (step S1405) in the operationexecution command generating process (step S1207). Also, these tablesare convoluted as shown in FIG. 24E by the condition table mergingprocess (step S1406), and connected as shown in FIG. 24F by theexecution sequence generating process (step S1407).

Specifically, as shown in FIG. 24F, the execution sequence is generatedsuch that the content D is rendered first, then the content C isrendered. The content B is rendered in such a manner as to be arrangedbelow the content C after rendering of the content C, and the content Ais rendered in such a manner as to be arranged below the content B afterrendering of the content B.

As described above, when the constraint shown in FIG. 24A is defined,each content is rendered in such a manner as to satisfy the particularconstraint.

In the case of FIG. 25, the constraint is defined between the fivecontents including the contents A1 to D shown in FIG. 25A. Specifically,the constraint is defined for rendering the content A1 at the same timeas the content D, and for rendering the content A2 below and after thecontent B, and for rendering the content B below the content C. FIGS.25B to 25F show the specifics of each table from designation ofrendering of the content A to the generation of the execution sequencein the presence of the constraint described above.

In the case of FIG. 25, as shown in FIG. 25F, the execution sequence isgenerated so that the content A1 and the content D are rendered at thesame time first, then the content C is rendered. The content B isrendered after the content C in such a manner as to be arranged belowthe content C, and the content A2 is rendered after the content B insuch a manner as to be arranged below the content B.

In the case of FIG. 26, the constraint between the three contentsincluding the contents A to C shown in FIG. 26A is defined.Specifically, the constraint is defined for rendering the content Abelow and after the content B, and rendering the content B below andbefore the content C. FIGS. 26B to 26F show the specifics of each tableup to the execution sequence generation upon designation of rendering ofthe content A in the presence of the aforementioned constraint.

In the case of FIG. 26, as shown in FIG. 26F, the execution sequence isgenerated so that the content B is rendered first, the content A isrendered after the content B in such a manner as to be arranged belowthe content B, and the content C is rendered after the content B in sucha manner as to be arranged above the content B.

In the case of FIG. 27, the constraint between the two contentsincluding the contents A and B shown in FIG. 27A is defined.Specifically, the constraint is defined for rendering the content Abelow and after the content B and rendering the content B above andbefore the content A. FIGS. 27B to 27F show the specifics of each tableup to the execution sequence generation upon designation of rendering ofthe content A in the presence of the aforementioned constraint.

In the case of FIG. 27, as shown in FIG. 27F, the execution sequence isgenerated so that the content B is rendered first and the content A isrendered after the content B in such a manner as to be arranged belowthe content B.

FIG. 28 is a diagram that explains an example of content renderingexecuted based on the structural constraint in the digital contentrendering apparatus 100 according to this embodiment. In this case, theoriginal content is an electronic book (ContentA) configured of fourcontents including Section 1 (ContentA1) to Section 4 (ContentA4). Thiselectronic book can be rendered section by section, and each section hasa structural constraint of “isPartOf” with the book. When the renderingof ContentA1 is designated, therefore, the electronic book (ContentA)including only Section 1 is rendered.

As described above, when the constraint defined between two contentsexists in the digital content rendering apparatus 100, the rendering ofeach content can be executed in such a manner as to satisfy theparticular constraint.

The digital content rendering apparatus 100 according to this embodimentcomprises a controller such as a CPU, a storage unit such as a ROM (readonly memory) or a RAM, an external storage unit such as a HDD or a CDdrive, a display unit such as a display unit and an input device such asa keyboard or a mouse. The apparatus 100 thus is configured of hardwareusing the normal computer.

The digital content rendering program executed in the digital contentrendering apparatus 100 according to this embodiment is provided bybeing recorded in a computer-readable recording medium such as a CD-ROM,a flexible disk (FD), CD-R or DVD (digital versatile disk) in the formadapted to be installed or executed.

Also, the digital content rendering program executed in the digitalcontent rendering apparatus 100 according to this embodiment may beconfigured to be provided by being stored on the computer connected to anetwork such as the internet and downloaded through the network.Further, the digital content rendering program executed in the digitalcontent rendering apparatus 100 according to this embodiment may beconfigured to be provided or distributed through a network such as theinternet.

The digital content rendering program according to this embodiment maybe configured to be provided by being built in a ROM or the like inadvance.

The digital content rendering program executed in the digital contentrendering apparatus 100 according to this embodiment is configured ofmodules including the parts described above (the content storagecontroller, the content designation receiver, the license processor, theuse condition determining unit, the content renderer, the operationexecution command generator, and the rendering history data storageunit). As actual hardware, the CPU (processor) executes by reading thedigital content rendering program from a storage medium. In this way,each part described above is loaded onto the main storage unit, so thatthe content storage controller, the content designation receiver, thelicense processor, the use condition determining unit, the contentrenderer, the operation execution command generator and the renderinghistory data storage unit are generated on the main storage unit.

As described above, the digital content rendering apparatus according tothe invention, the digital content rendering method, the digital contentrendering program and the recording medium for recording the digitalcontent rendering program according to this invention are suitablyapplicable to the digital content rendering apparatus for rendering thedigital contents based on the license information defining the specificsof permission of the rendering operation.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. An apparatus for rendering a digital content having licenseinformation, comprising: a license processor that acquires a constraintfrom the license information defining specifics of permission of arendering operation of the digital content, the constraint definingconditions between rendering of the digital content designated forrendering and rendering of a constraint content other than the digitalcontent designated for rendering; an operation execution commandgenerator that generates an operation execution command for renderingthe digital content designed for rendering and the constraint contentaccording to the constraint acquired by the license processor; and acontent renderer that renders the digital content designated forrendering and the constraint content based on the operation executioncommand generated by the operation execution command generator, whereinthe license processor acquires, as a constraint, a time constraintindicating a chronological relationship between the digital content andthe constraint content, the chronological relationship being selectedfrom a group including at least a relationship indicating the digitalcontent is rendered before the constraint content, a relationshipindicating the digital content is rendered after the constraint content,and a relationship indicating the digital content is renderedsimultaneously with the constraint content, and the operation executioncommand generator generates an operation execution command for renderingthe digital content and the constraint content according to thechronological relationship defined in the time constraint acquired bythe license processor.
 2. An apparatus for rendering a digital contenthaving license information, comprising: a license processor thatacquires a constraint from the license information defining specifics ofpermission of a rendering operation of the digital content, theconstraint defining conditions between rendering of the digital contentdesignated for rendering and rendering of a constraint content otherthan the digital content designated for rendering; an operationexecution command generator that generates an operation executioncommand for rendering the digital content designated for rendering andthe constraint content according to the constraint acquired by thelicense processor; and a content renderer that renders the digitalcontent designated for rendering and the constraint content based on theoperation execution command generated by the operation execution commandgenerator, wherein the license processor acquires, as a constraint, anexclusive constraint indicating a disabled relationship between thedigital content and the constraint content, and the operation executioncommand generator generates, according to the exclusive constraintacquired by the license processor, an operation execution command fornot rendering the digital content having the exclusive constraint whenthe constraint content prohibited from being used together with thedigital content is being rendered.
 3. An apparatus for rendering adigital content having license information, comprising: a licenseprocessor that acquires a constraint from the license informationdefining specifics of permission of a rendering operation of the digitalcontent, the constraint defining conditions between rendering of thedigital content designated for rendering and rendering of a constraintcontent other than the digital content designated for rendering; anoperation execution command generator that generates an operationexecution command for rendering the digital content designated forrendering and the constraint content according to the constraintacquired by the license processor; and a content renderer that rendersthe digital content designated for rendering and the constraint contentbased on the operation execution command generated by the operationexecution command generator, wherein the license processor acquires, asa constraint, a structural constraint indicating a structuralrelationship between the digital content and the constraint content, thestructural relationship indicating the digital content is included inthe constraint content or vice versa, the operation execution commandgenerator generates an operation execution command for rendering thedigital content and the constraint content according to the structuralrelationship defined in the structural constraint acquired by thelicense processor.
 4. A computer readable storage medium encoded withinstructions, which when executed by a computer, causes the computer toimplement a method comprising: acquiring, by the computer, a constraintfrom license information of a digital content, the constraint definingconditions between rendering of the digital content designated forrendering and rendering of a constraint content other than the digitalcontent designated for rendering, the license information definingspecifics of permission of a rendering operation; generating anoperation execution command for rendering the digital content designatedfor rendering and the constraint content according to the constraint;and rendering the digital content designated for rendering and theconstraint content based on the operation execution command, wherein theacquiring includes acquiring, as a constraint, a time constraintindicating a chronological relationship between the digital content andthe constraint content, the chronological relationship being selectedfrom a group including at least a relationship indicating the digitalcontent is rendered before the constraint content, a relationshipindicating the digital content is rendered after the constraint content,and a relationship indicating the digital content is renderedsimultaneously with the constraint content, and the generating includesgenerating an operation execution command for rendering the digitalcontent and the constraint content according to the chronologicalrelationship defined in the time constraint.
 5. A computer readablestorage medium encoded with instructions, which when executed by acomputer, causes the computer to implement a method comprising:acquiring, by the computer, a constraint from license information of adigital content, the constraint defining conditions between rendering ofthe digital content designated for rendering and rendering of aconstraint content other than the digital content designated forrendering, the license information defining specifics of permission of arendering operation; generating an operation execution command forrendering the digital content designated for rendering and theconstraint content according to the constraint; and rendering thedigital content designated for rendering and the constraint contentbased on the operation execution command, wherein the acquiring includesacquiring, as a constraint, an exclusive constraint indicating adisabled relationship between the digital content and the constraintcontent, and the generating includes generating, according to theexclusive constraint, an operation execution command for not renderingthe digital content having the exclusive constraint when the constraintcontent prohibited from being used together with the digital content isbeing rendered.